This invention relates to the production of a new form of alkali metal silicate glass and in particular is concerned with soluble silicate disks that do not fracture and therefore result in virtually dust free products.
Molten alkali metal silicate glass that is not to be utilized for immediate dissolution is generally cast in iron molds that are approximately 21/2 inches (6.35 cm) square by 1/2 to 3/4 inches (1.27 to 1.90 cm) deep. The resulting glass chunks are usually thicker than the depth of the molds unless a leveling roll is used to flatten the glass before it cools and becomes rigid. The glass cooled in such molds is highly stressed; subsequent handling and crushing causes fractures and shattering thereby producing large numbers of very fine particles. Highly stressed glass is also produced when sheets of alkali metal silicate glass are cooled quickly as described in U.S. Pat. No. 3,734,756 issued May 22, 1973, which is hereby incorporated by reference. Handling and crushing of this product also produces many fines and dusty products result.
The fine particles generated when these glass forms are handled or crushed are distinct disadvantages. The ultimate silicate products are dusty and at worst can pose a safety hazard and at best a clean-up problem. Upon dissolving a glass with a large proportion of very fine particles, they agglomerate forming a "sticker". Such a mass of hydrated glass particles does not disperse or dissolve readily and can cause numerous problems in the dissolving equipment.